Four-way plug valve

ABSTRACT

A rotary lift-turn type plug valve mechanism includes a valve body and bonnet structure defining a tapered valve chamber that receives a tapered plug member which is operated by linear and rotary components of movement to achieve valve operation. Externally adjustable plug positioning means is provided by the valve mechanism to enable the position of the plug element to be adjusted relative to the inlet and outlet flow passages defined by the valve body. Plug dampening means is also provided for applying a dampening force to the plug element to prevent slamming of the plug upon reaching the end of a rotational component of movement. A valve actuator is also provided that operatively engages the valve stem of the plug and is capable of imparting both linear and rotary components of movement to the valve stem for unseating, rotating and reseating the valve element within the valve chamber. A system is provided for maintenance of predetermined pressure differential across the sealing elements of the valve and to compensate for volumetric changes as the valve element is seated and unseated.

FIELD OF THE INVENTION

This invention relates generally to rotary plug valves and, inparticular, four-way plug valves that control the flow of fluid in aflow conduit system. More particularly, the present invention relates toa lift plug type plug valve mechanism wherein the plug element and valvechamber of the valve are of frusto-conical mating configuration and theplug element is operated by a linear unseating movement, a rotationalmovement to reposition the plug element relative to the flow conduitsystem and an opposite linear movement for reseating the plug elementrelative to the seating surfaces defined by the valve chamber. Even morespecifically, the present invention relates to a rotary plug valvemechanism incorporating externally adjustable means for properorientation of the plug element relative to inlet and outlet flowpassages and a dampening system for preventing slamming of the plugelement as it reaches an extremity of its rotational movement.

BACKGROUND OF THE INVENTION

It will be apparent from the following disclosure that the presentinvention has particular utility in conjunction with four-way type plugvalves. It should be borne in mind, however, that the present inventionalso has utility from the standpoint of rotary plug valves other thanfour-way plug valves. For purposes of simplicity, however, the inventionis described particularly as it relates to four-way plug valvemechanisms.

Plug valves may be classified in three basic classes, i.e. cylindricalplug valves, tapered or conical plug valves and spherical plug valves,which are commonly referred to as ball valves. With regard specificallyto tapered plug valves, these may be classified as simple rotary valveswherein the plug element is simply rotated within the valve body forcontrolling the flow of movement through the valve mechanism. In orderto protect the sealing elements and sealing surfaces of tapered plugvalves from excessive wear, plug valves have been developed that areoperated by lifting the tapered plug element or shifting it linearly tounseat or separate the sealing element of the plug from the seatingsurfaces defined within the valve body. After the unseating movement,the plug element is then rotated to the proper position and is thenmoved linearly in the opposite direction to again seat the sealingelement of the plug in sealing engagement with the seating surfaces ofthe valve body. As the plug element is rotated during operation of thevalve mechanism, the sealing element often carried by the plug is not inengagement with any internal seating surfaces and therefore no wearoccurs during such movement. The service life of such lift-turn typeplug valves is therefore materially enhanced. Providing a lift-turncapability for plug valve mechanisms is especially important when largeplug valves are employed because of the length of seal travel duringoperational movements.

When four-way type lift plug valve mechanisms are incorporated in meterprover systems, it is necessary for such valve mechanisms to be cycledquite frequently. It is therefore desirable to provide a plug valvemechanism that does not become excessively worn because of rapid,frequent cycling.

Where large plug valves are employed in fluid flow control apparatus,such as flowmeter loops, the valve mechanisms are typically cycled quiterapidly, i.e. moved from one operative position to another in a periodof several seconds duration. Where the plug valve mechanisms are oflarge size, the internal rotatable plug elements will be quite massiveand will have considerable weight. Typically, forces of inertianecessary to start and stop the rotational movement of the plug elementis absorbed by the structural components of the valve actuator thatachieves linear and rotational movement of the plug. Because of thesevere inertia forces that are transmitted to the valve actuator systemare quite severe, the valve actuator mechanism is typically of extremelydurable and expensive manufacture in order to compensate for theseforces as much as possible. Ordinarily, inertia forces are notexcessively severe as rotational movement of the plug element isinitiated. At the end of the rotational stroke, however, the valveactuator is suddenly stopped and a severe inertial force will betransmitted from the plug member through the valve actuator mechanism asrotational movement of the plug member is abruptly stopped. It isdesirable to provide means for insuring the severe inertial forces arenot transmitted to the valve actuator mechanism. This will insure thatthe valve actuator will provide extended service life and willfacilitate less expensive manufacture of the valve actuator mechanism.

As the valve actuator and other valve components become worn, it istypical for the flow port of the plug member to become misaligned withrespect to the inlet and outlet passages of the valve mechanism. Whenthe port is misaligned with the inlet and outlet flow passages,turbulence can be developed that will impede the flow of fluid throughthe valve mechanism. Also, especially in large valve mechanisms, theseat surfaces and sealing surfaces of the valve body and plug member maybecome misaligned if the position of the plug at the end of itsoperational stroke becomes changed. In this case, the valve will notseal properly and must be typically disassembled for repair.Alternatively, in some cases the valve actuator may be adjusted tomodify the stopping position of the plug member, depending upon thecharacteristics of the valve actuator. It is desirable to provide meansfor simply and efficiently adjusting the stopping position of the plugmember within the valve body and it is also desirable to provideadjustment means that is capable of external adjustment to insureagainst the necessity to disassemble the valve for adjustment.

Where a high degree of seal integrity is mandatory in plug valvemechanisms, it is desirable to determine if a proper seal is establishedeach time the plug member is shifted linearly to a sealing position. Ifthe valve should leak even a small amount with the plug at its sealingposition, then it may be necessary to disregard a meter loop measurementfor the purpose of checking the accuracy of a flowmeter. It is desirableto insure that the four-way plug valve is sealing properly at eachoperational run of the flowmeter loop in order that the known volume ofthe flowmeter loop may be checked against the particular measurement ofthe flowmeter involved. It is desirable to provide means for insuringthe seal integrity of the plug valve mechanism during each prover run.

In some cases, the tapered plug elements of lift-turn type four-way plugvalves are formed to define pairs of seal grooves and sealing material,such as a suitable elastomeric or plastic material, is molded withinthese grooves in order to define the sealing elements of the plug. Inthe event these molded seal elements become worn to the point thatreplacement is desired, the valve must be disassembled to remove theplug element. Typically, to place the valve back in service as soon aspossible, a substitute plug is installed. The plug member having theworn seal is then transferred to a repair facility where the sealgrooves will be cleaned and new sealing material installed. Thereconditioned plug member will then be placed in readiness for futurerepair operations. In other cases, the tapered plug members are formedto define grooves having small seal openings through which the sealingportion of sealing elements extend with the seal grooves being formed tomechanically retain the sealing elements against displacement from theseal groove by the forces of the flowing fluid. These types of seals arenot typically satisfactory because they are rather easily extruded fromthe seal grooves by fluid forces and are rather easily damaged. Whenservicing is required, however, these types of plugs can be repairedvery simply by removing the worn or damaged seals and by simplyinserting replacement seals. It is desirable to provide a plug valvemechanism incorporating sealing elements that are field replaceable butwhich are mechanically retained within seal grooves to the extent thatthe seals will effectively resist ordinary seal extrusion and damage andwill function quite satisfactorily at high operating pressures or underthe influence of high volume fluid flow.

When tapered rotary plug valves are lifted for unseating and moveddownwardly for seating movement as well as being rotated during fluidcontrolling movement, differential volumetric changes typically occur.The spaces defined between the valve element and the large and smallextremities of the valve typically vary substantially in volume. Duringseating and unseating movement, the plug member is moved linearly withseals established between the plug member and the inner surfaces of thevalve body. During such plug movement negative and positive fluidpressures typically develop that retard plug movement and thereforesubject the valve actuator system to greater forces than might bedesirable. It is desirable to provide means for insuring maintenance ofa predetermined maximum pressure differential across the sealingelements of the valve during seating and unseating movement and tominimize the effect of any operator retarding forces due to positive andnegative pressures.

In view of the foregoing, it is a primary feature of the presentinvention to provide a novel four-way lift plug type valve mechanismincorporating a dampening system that effectively reduces inertialforces that might otherwise be transmitted from the rotatable plugmember to the valve actuating mechanism thereof.

It is also a feature of the present invention to provide a novelfour-way lift turn type plug valve mechanism that incorporates anexternally adjustable plug positioning mechanism that allows thestopping position of the plug at the end of its rotational movement tobe changed without necessitating disassembly of the valve mechanism ormodification of the valve actuator system.

Among the several features of the present invention is contemplated anovel lift-turn type plug valve mechanism incorporating means forchecking the integrity of the seal each time the plug member ispositioned at the seal position thereof.

It is also a feature of the present invention to provide a four-way liftturn type plug valve mechanism incorporating a fluid transfer system forpurposes of dampening rotational movement of the plug element, whichfluid dampening system incorporates a pair of schematically parallelfluid flow conduits, each including relief valves for allowingunidirectional flow of dampening fluid through each of the schematicallyparallel conduits.

It is a further feature of the present invention to incorporate inconjunction with a four-way lift turn type valve mechanism a pluralrelief valve system allowing fluid flow at different selected pressuresdepending upon the direction of flow through the relief valve mechanism.

It is also a feature of the present invention to incorporate inconjunction with a four-way plug valve mechanism a plural relief valvesystem incorporating two relief valves with the flow of fluid in onedirection through the relief valve mechanism causing opening of a firstrelief valve while simultaneously applying a closing fluid pressure tothe second relief valve and flow of dampening fluid in the oppositedirection through the relief valve mechanism induces opening of thesecond relief valve while simultaneously assisting in closure of thefirst relief valve.

It is another provision of this invention to provide a novel four-wayvalve mechanism having the capability of compensating for volumetricchanges within the valve chamber and minimizing any actuator retardingforces that might otherwise develop.

Other and further objects, advantages and features of the presentinvention will become apparent to one skilled in the art uponconsideration of this entire disclosure. The form of the invention,which will now be described in detail, illustrates the generalprinciples of the invention, but it is to be understood that thisdetailed description is not to be taken as limiting the scope of thepresent invention.

SUMMARY OF THE INVENTION

In accordance with the present invention, a four-way lift-turn typerotary plug valve is provided which includes a tapered plug member thatis operated within a valve body by both linear and rotary components ofmovement. The plug member is moved linearly for unseating the sealingelements of the plug from the seating surfaces defined within the valvebody and is then rotated to a preselected position. After rotation, theplug member is again moved linearly to reseat the sealing elements ofthe plug in sealing engagement with the seating surfaces of the valvebody. To position the plug member in accurate registry with the inletand outlet passages of the valve mechanism, a plug positioning elementextends through an aperture formed in the valve bonnet and positions aneccentric portion thereof within the valve chamber. A detent or stopprojection provided on the plug member is moved into engagement with theeccentric portion of the plug positioning element to provide a stop forpositioning the plug with respect to the inlet and outlet flow passages.To enable the stop position of the plug to be changed, the eccentricstop portion of the plug positioning element may be selectivelyoriented. The plug positioning element is formed to define a flangehaving a plurality of bolt openings formed therein that may be broughtinto registry with internally threaded bolt openings formed in thebonnet structure of the valve. By simply unbolting the flange of theplug positioning element and rotating it to align the bolt openingsthereof with respect to other ones of the internally threaded boltopenings, the position of the eccentric portion of the plug positioningelement will be changed slightly and the stop projection of the plugmember will engage a different portion of the eccentric surface, thusslightly altering the position of registry between the plug member andthe valve body.

The plug element is formed to define seal recess grooves at the upperand lower portions thereof for receiving pairs of sealing elements. Sealretainer elements, including an elongated retainer bar cooperating witha pair of retainer end pieces, functions cooperatively with the plugstructure to define opposed parallel groove portions for retainingportions of each of the sealing elements.

Apparatus is also provided for determining the integrity of the sealthat is established each time the plug element is moved into the sealingposition thereof. The seal detection apparatus incorporates means fordetecting pressure changes within the valve chamber after the sealingelements have been brought into sealing engagement with the body. Suchpressure changes indicate that a proper seal has not been established. Apressure responsive switch or other monitoring system may be utilized inconjunction with the valve chamber to enable the pressure within thevalve chamber to be inspected electrically and to insure automaticrejection of flowmeter runs in the event the value should fail toestablish a proper seal when seated.

Apparatus is also provided to compensate for volumetric changes as theplug element is moved linearly during seating and unseating movement andto prevent the development of excessive positive and negative pressuresduring such seating and unseating movements. A fluid flow passage isformed in the plug element for the purpose of placing the upper andlower portions of the valve chamber in communication, thus insuringpressure balancing of the upper and lower portions of the valve chamber.To insure maintenance of a predetermined maximum pressure differentialacross the sealing elements of the valve, thus preventing thedevelopment of a severe operator retarding force due to volumetricdifferentiation between the upper and lower portions of the valvechamber, a fluid compensating conduit or circuit is provided thatinterconnects the upper or large volume portion of the valve chamberwith one of the flow passages of the valve. This circuit incorporates avalving and fluid metering arrangement automatically allowing fluidinterchange between the valve chamber and flow passage of the valve inthe event volumetric fluid differentiation should increase or decreasefluid pressures within the valve chamber beyond a predeterminedacceptable pressure range. For example, the valving and meteringarrangement might be set to maintain a positive or negative pressuredifferentiation of 25 p.s.i. between the valve chamber and flow passagewith the plug member of the valve during seating and unseating movement.

Also incorporated into the valve mechanism is a dampening system thatprovides cushioning capability to prevent slamming of the plug member asit reaches the end of its rotary travel during operation. The dampeningsystem may incorporate a dampening housing defined either externally orinternally of the valve body structure and the dampening chamber may befilled with a dampening medium, such as hydraulic oil, for example. Avane element may be positioned within the dampening housing in suchmanner as to divide the dampening housing into first and seconddampening chambers. A dampening passage system may be provided havingone extremity thereof in communication with one of the dampeningchambers and with the opposite extremity in communication with theopposite dampening chamber. The vane element, which may be connected tothe valve stem or trunnion, depending upon the character of thedampening system utilized, will be rotated within the dampening housingand will cause dampening fluid to be forced from one of the dampeningchambers to the opposite dampening chamber. A relief valve system may beincorporated into the dampening conduit system so as to provide arestriction to the free flow of fluid between the dampening chambers.This restriction to fluid flow will provide an opposing force that istransmitted to the plug element, opposing free rotation of the plugelement. As the plug element reaches the end of its operational strokeor rotary movement, any tendency of the plug member to slam or applysevere inertia induced loading to the valve actuator mechanism will beminimized. For the purpose of achieving dampening regardless of thedirection of fluid flow through the dampening passage system, a pair ofconduits may be connected in schematically parallel relation with eachconduit incorporating a relief valve capable of allowing unidirectionalrestricted fluid flow. The plural opposing relief valves may beincorporated in a single relief valve structure and may be simplyconnected into a single dampening passage interconnecting the dampeningchambers.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, as well as other objectsand further features thereof, reference is made to the followingdetailed description to be read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a diagrammatic representation in plan, illustrating abidirectional meter prover loop system incorporating a four-way divertervalve for controlling operation thereof and further showingcounterclockwise flow through the meter prover loop.

FIG. 2 is a diagrammatic representation as in FIG. 1, illustrating thevalve element at an intermediate position during movement between theoperative positions of FIGS. 1 and 3. In such position fluid by-passesthe meter prover loop and flows directly between the inlet and outletpassages.

FIG. 3 is a diagrammatic representation as in FIGS. 1 and 2 illustratingthe four-way diverter valve as being positioned to cause clockwise flowthrough the meter prover loop.

FIG. 4 is an elevational view of a valve and actuator assemblyconstructed in accordance with the principles of the present inventionwith the valve structure being broken away and shown in section and withthe valve element shown seated and at an intermediate position tofacilitate a ready understanding of the valve construction.

FIG. 5 is a sectional view taken along lines 5--5 of FIG. 4 andillustrating the dampening system of the valve mechanism in section withthe dampening fluid transfer system thereof shown schematically.

FIG. 6 is a fragmentary sectional view of the valve mechanism of FIG. 4illustrating the plug member thereof in its raised or unseated positionand further illustrating mechanical structure for retaining the sealingelements of the plug member in positive mechanically retainedrelationship relative to the structure of the plug valve.

FIG. 7 is a fragmentary vertical section of the plug structureillustrating further details of mechanical apparatus for retaining thesealing element in mechanically interlocked relationship with the plugstructure and showing a pressure equalizing passage being formed in thevane portion of the plug member.

FIG. 8 is a fragmentary sectional view illustrating the seal and sealretainer structure in detail.

FIG. 9 is a partial elevational view of the plug structure of FIGS. 4and 6, illustrating further details of the seal retainer structure.

FIG. 10 is a fragmentary sectional view taken along lines 10--10 of FIG.9 and illustrating further mechanical details of the apparatus forretaining the sealing elements in interlocked relationship with the plugstructure.

FIG. 11 is a partial sectional view of a four-way valve mechanismconstructed according to the present invention and incorporating apressure responsive pressure multiplying system for insuring maintenanceof a positive pressure in the valve chamber to enhance the seatingability of the valve element.

FIG. 12 is a sectional view of a four-way valve mechanism constructedaccording to this invention and incorporating a system for achievingautomatic body venting and positive pressure seating to enhance thesealing ability of the valve element.

FIG. 13 is a diagrammatic representation of a plug position adjustmentmechanism illustrating the allowable limits of plug positioning that isavailable upon 180° adjustment of the positioning mechanism.

FIG. 14 is a sectional view of a restrictor valve mechanism that isadapted to control communication between the valve chamber and flowpassage of the valve and insure maintenance of a predetermined pressuredifferential range between the valve chamber and flow passage.

FIG. 15 is a sectional view of a restrictor valve representing amodified embodiment of the present invention and utilizing sleeve typevalve elements for controlling the direction of fluid flow through therestrictor valve mechanism and establishing the selected pressuredifferential range.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawings and first to FIGS. 1-3, there is shown afour-way valve mechanism generally at 10 that is interconnected with abidirectional meter prover loop 11. The valve 10 is positionable tocontrol the flow of fluid from inlet and outlet conduits and achievereversible flow within the flow-meter loop. In FIG. 1, the valvemechanism is positioned to direct the flow of fluid from the inletthrough the meter prover loop in a counterclockwise direction. The fluidmeasurement occurs as ball B causes initiation of the measuring run atswitch S₁ and terminates the measuring run upon subsequent actuation ofswitch S₂. In FIG. 2, the valve mechanism is shown at an intermediateposition during movement between the operative positions of FIGS. 1 and3. In this intermediate condition fluid flow from the inlet passageflows directly to the outlet passage without directing a flow conditionhrough the meter prover loop. At this stage of valve movement, themoving fluid within the loop begins to slow its flow for reversal whenthe valve movement is completed. In FIG. 3, the valve mechanism ispositioned to reverse the flow of fluid through the meter prover loop,thus achieving clockwise flow. In this case, the prover run is initiatedas the ball B actuates the switch S₂ and the measurement terminates asswitch S₁ is tripped by passage of the ball. The volume of the proverloop between switches S₁ and S₂ is known and the flow rate is determinedby the lapse of time between actuation of switches S₁ and S₂. Of course,when the fluid is a gas, other factors must be considered in order toestablish accurate measurement. Moreover, positive sealing of the valvemechanism is required for the accuracy of flow measurement for thereason that any leakage of the valve would cause inaccurate measurementof the flow rate.

Referring now to FIG. 4, a four-way lift turn type plug valve isillustrated generally at 10 and includes a valve body structure 12defining a valve chamber 14 of frusto-conical configuration and defininga frusto-conical sealing surface 16. The valve body structure alsodefines four inlet and outlet passageways, two of which are illustratedat 18 and 20, and further provides connection flanges, such as shown at22 and 24, or other suitable connection means for establishingconnection between the valve mechanism and a flow conduit system. Thevalve body structure is formed to define an upper opening 26 that isclosed by means of a bonnet structure 28 that is retained in assemblywith the body structure by means of a plurality of bolts 30 that extendthrough appropriate apertures formed in the bonnet and are receivedwithin threaded apertures formed in the valve body structure about theopening 26. An annular sealing element 32, such as an O-ring, or thelike, is retained within an annular groove formed at the upper extremityof the valve body to provide a positive fluid tight seal between thevalve body and bonnet structure.

Within the valve chamber 14 is movably positioned a plug element 34 thatis of generally tapered or frusto-conical configuration and which isadapted for mating engagement with the frusto-conical sealing surface 16defined by the valve body. The plug member 34 is supported for rotationwithin the valve body 12 by a valve stem 36 and a trunnion 38 thatextend in nonrotatable relation from opposed extremities of the plugelement. The bonnet structure 28 is formed to define a step passage 40through which the valve step 36 extends. A sealed relationship betweenthe valve stem and the bonnet is maintained by a packing assembly 42that is retained within a packing chamber defined immediately above arestricted portion of the valve stem passage 40. A packing gland orretainer 44 may be secured to the bonnet structure 28 by bolts 46 forthe purpose of retaining the packing assembly 42 within the packingchamber. A bearing element 48 is positioned about the valve stem 36 andis received within a bearing receptacle 50 defined within the bonnetstructure. The bearing 48 provides bearing support for the valve stem 36and may be formed of any suitable bearing material that is compatiblewith the material of the valve stem.

To facilitate ready understanding of the structure of the valveconstruction, the valve element 34 is shown in FIGS. 4, 11 and 12 at anintermediate position such as in FIG. 2 and is shown seated. Inoperation, the true intermediate and unseated relation of the plug isshown in FIG. 6, and in FIGS. 1 and 3.

In order to operate the plug member 34 within the valve body, the valvemechanism may be provided with a valve actuator illustrated generally at52 having a base connector flange 54 that may be secured to the bonnetstructure 28 of the valve by means of a plurality of bolts 56. The valveactuator mechanism will typically be powered and is provided with amotor connector flange 58 from which extends a connector shaft 60 of thevalve actuator. A reversible electric motor may be secured to the flange58 by means of bolts, or any other suitable means of connection, and anonrotatable connection may be established between the actuator shaft 60and the motor shaft, not shown, in order that the motor may impartrotary movement to the shaft 60 and thus achieve power operation of thevalve actuator. Any one of a number of suitable types of valve actuatorsmay be employed within the spirit and scope of the present invention, itbeing only necessary that the valve actuator mechanism be capable ofimparting both linear and rotary movement to the valve stem 36 forunseating, rotating and reseating the plug member 34 with respect to thesealing surfaces defined within the valve body. For operation of thevalve as illustrated in FIG. 4, the actuator mechanism first moves thevalve stem 36 linearly in an upward direction sufficiently to separatethe sealing element of the plug from the sealing surfaces of the valve.After this has been accomplished, the plug member will be rotated by thevalve actuator to a preselected position within the valve chamber. Afterthis has been accomplished, the valve actuator will move the valve stemlinearly in a downward direction so as to cause the tapered plug memberto again be reseated in sealing engagement with respect to the seatingsurfaces defined within the valve chamber.

As mentioned above, the plug element of large valve will be quitemassive and will develop considerable inertia forces as it is stopped atits preselected position by the valve actuator. It is desirable toprovide a dampening system that prevents free rotation of the plugmember and which provides dampening forces that oppose the inertialforces of the plug member. This feature will prevent a conditionreferred to as slamming which, as explained above, can cause seriousdamage and excessive wear to the valve actuator mechanism. In accordancewith the present invention and as illustrated at the lower portion ofFIG. 4 and in FIG. 5, one suitable means for inducing dampening forcesto the rotating plug member may be accomplished as follows. At the lowerportion of the valve body 12 an aperture 62 may be formed within whichmay be received the extension portion 64 of a packing and bearing insert66. A bearing 68 which may be similar to the bearing 48 described abovemay be received within a bearing receptacle defined in the extensionportion 64 of the insert 66. The bearing 68 will provide an appropriatebearing journal for the trunnion element 38 thereby preventing excessivewear of the trunnion or valve body responsive to rotation of thetrunnion during valve operation. The packing and bearing insert 66 maybe retained in assembly with the valve body 12 by means of bolts 70 thatextend through a flange portion 72 of the insert. Bolts 70 also extendthrough elongated bolt passages formed in a dampener housing 74. Thepacking and bearing insert defines a trunnion passage 76 through whichthe trunnion 38 extends. A portion of the trunnion passage may bedefined by a packing chamber within which may be received a packingassembly 78 that establishes a fluid tight seal between the packing andbearing insert and the trunnion 38. A packing retainer element orpacking gland 80 may be secured to the packing and bearing insert 66 bymeans of a plurality of bolts 82 for the purpose of retaining thepacking assembly 78 in position within the packing chamber. The packinggland incorporates an internal seal element 84 that establishes a sealbetween the packing gland and the trunnion 38 outwardly of the packingassembly 78.

The dampening housing 74 is formed internally to define an internalreceptacle 86 that is closed by means of a partial cover plate or bonnet88 secured to the dampening housing by means of the bolts 70. A sealingelement 90 is interposed between the cover plate and the dampeninghousing in order to provide an appropriate seal for the dampeningchamber 86. The lower extremity of the trunnion element 38 may be formedto define external splines 92 that are received in splined connectionwith an internal splined receptacle 94 formed in a vane element 96 thatis positioned within the dampening chamber 86. A lower circular portionof the vane element is positioned within a central aperture defined bythe partial cover plate. Internal seal element 98, such as O-rings orthe like, may be retained within annular seal grooves formed in opposedcylindrical portions of the vane element for the purpose of establishinga seal between the dampening housing and the upper portion of the vaneelement 38 and between the partial bonnet 88 and the lower portion ofthe vane element. The splined connection between the trunnion and thevane element establishes a nonrotatable relationship therebetween butallows the trunnion element to move linearly as is necessitated bylinear movement of the valve stem and plug element to accommodate theunseating and reseating movements described above. The lower extremityof the trunnion 38 is exposed to the atmosphere.

With reference now to FIG. 5, which is a transverse section taken alongline 5--5 of FIG. 4, the dampening housing 74 may be formed to defineinternal projecting portions 100 and 102 that define limits ofrotational travel of the vane element 96 within the dampening housing.The vane element cooperates with the housing structure and with theinternal projections 100 and 102 to define first and second dampeningchambers 104 and 106. As shown schematically in FIG. 5, a dampeninginterchange passage or conduit system is illustrated, having itsextremities 108 and 110 interconnected with the housing structure 74 andin communication with respective ones of the dampening chambers 104 and106. The dampening fluid interchange system, as shown in FIG. 5,incorporates a conduit or passage 112 having a flow controller showngenerally at 114 interconnected therein which allows unrestricted fluidflow through the conduit 112 in one direction while restricting flow inthe opposite direction. A check valve 115 is connected into a bypassconduit 116 that is, in turn, connected across a variable restrictorvalve 117. With the check valve 115 seated and preventing flow throughthe by-pass conduit 116, flow across the restrictor valve is retarded. Asecond flow controller, illustrated generally at 118 by the broken line,is also interconnected into conduit 112 and functions in the same manneras controller 114. Controller 118 includes a bypass line 119 connectedacross a variable restrictor valve 120 with a check valve 121 allowingfree flow of fluid through the bypass line in one direction. Checkvalves 115 and 121 are oppositely oriented in the respective bypasslines, causing fluid flow to be directed across one of the variablerestrictor valves in each direction of flow. For example, flow in thedirection of the flow arrow is blocked by check valve 115 and thus flowsacross the restrictor valve 117. Such flow then passes freely throughthe flow controller because of the orientation of check valve 121. Thus,flow in the direction of the flow arrow is restricted by the restrictorvalve 117 and the degree of restriction can be controlled to insureproper counterclockwise movement of the vane 96. For separate control ofthe clockwise movement of the vane element, to develop a differingdampening effect as compared with counterclockwise dampening, flow inthe opposite direction through the conduit 112 is restricted only byrestrictor valve 120. Flow through the bypass line 119 is blocked bycheck valve 121 but check valve 115 allows free flow through bypass line116.

As the valve actuator 52 imparts rotary movement to the valve stem 36,the plug 34 and the trunnion element 38, the trunnion, with its splinedconnection with the vane element 96, causes the vane element to rotatewithin the dampening housing 74. Assuming the second dampening chamber106 to be filled with a dampening fluid, such as hydraulic fluid, forexample, counterclockwise movement of the vane element will causedampening fluid to be ejected from one of the dampening chambers 104 and106, whereupon the dampening fluid will flow through the flowcontrollers being restricted due to the particular setting of thevariable restrictor valve 117 or 120. The fluid will then flow into theopposite one of the dampening chambers 104 and 106 to fill the void thatis created by movement of the vane element. Upon movement of the vaneelement in the opposite direction, which is caused by rotation of thevalve stem plug and trunnion in the opposite direction, dampening fluidwithin the opposite one of the dampening chambers 104 and 106 will bedisplaced through the dampening conduit and across the opposite one ofthe flow controllers 114 and 118 before entering the opposite one of thedampening chambers.

As the dampening fluid flows through the flow controllers one of therestrictor valves will offer a preset amount of resistance to the freeflow of fluid. This resistance will manifest itself in imparting aretarding force or resistance to the trunnion, and thus to the rotatingplug and valve stem, which retarding force opposes the rotationalmovement induced by the valve actuator. This opposing force will preventthe plug member from slamming and developing an excessively large anddamaging force on the valve actuator as the valve actuator abruptlystops the plug element at its preset position. In fact, the opposingdampening force will assist the valve actuator in stopping the plugmember at the present position.

One of the more important aspects of controlling flow of fluid withfour-way type plug valves is the tendency of the valves to "windmill"during fluid diverting movement. As the valve is operated, during aninitial portion of valve movement the force of the valve actuator isimpeded by fluid force acting on the vane or valve element. As valvemovement continues, the force induced by fluid pressure changes suddenlyfrom opposing movement of the valve element to enhancing continuingmovement of the valve element. This sudden force change due towindmilling can result in severe mechanical shock to the valve andactuator mechanism. Moreover, the windmilling valve element can alsocause sudden and severe alteration of the flow characteristics throughthe valve. The flow controllers will also function cooperatively todampen and resist the windmilling effect that is prevalent in four-wayplug valves.

As shown in FIG. 6, the plug member 34 is lifted to the unseatedposition thereof and the sealing elements of the plug member are readilyvisible. It is desired that the plug member be provided with easilyreplaceable sealing elements in order that the valve mechanism may berepaired in the field should the sealing elements become worn or damagedduring use. It is also desirable that the plug member be such thatmanufacture will be relatively simple and inexpensive. As shown in FIG.4 and in more detail in FIGS. 6, 7 and 8, the upper and lower portionsof the plug member will be turned as by lathe operations to defineannular end recesses such as shown at 124 and 126 in FIG. 7. Upper andlower annular retainer rings 128 and 130 may be secured to the plugelement by a number of bolts 132 and 134 that extend through aperturesformed in each of the retainer elements. The retainer elements cooperatewith the plug structure to define an annular seal groove 136 withinwhich may be received a semi-annular portion of one of the sealingelements 138 and 140.

Each of the sealing elements is integrally formed and, as shown in FIG.6, the sealing elements are formed to define upper and lower generallysemicircular portions 142 and 144, respectively, that are joined bymeans of intermediate sections 146. The intermediate sections are ofsubstantially straight configuration and are formed to follow the taperdefined by the tapered side walls of the plug. As shown in FIG. 10, thestraight portions 146 of the seal members are received within elongatedgrooves 148 and 150 that are established by cooperative relationshipbetween a retainer element 152 and the structural wall portion 154 ofrotatable plug member 34. The elongated retainer element, as shown inFIGS. 9 and 10, is secured to the plug structure by means of a pluralityof bolts 156. As shown in the cross-sectional view of FIG. 10, the sealgrooves 148 and 150 are of L-shaped configuration that mate with theL-shaped configuration of the sealing elements. The base portions of thesealing elements are retained in position retainer elements. Likewise,as seen in FIG. 8, the L-shaped sealing element 138 is also entrappedwithin the corresponding L-shaped seal groove 136 by an internalshoulder defined by the retainer ring 128.

To provide ease of manufacture of the retainer elements 152, theretainer element is shown in FIG. 9 as terminating short of the upperand lower portions of the sealing elements. Upper and lower retainerfillet elements 158 and 160 are secured to the plug structure by meansof bolts 162 and 164 and function to provide curved transition from thestraight groove portions 148 and 150 to the semicircular upper and lowerportions of the seal grooves as shown at 136 in FIG. 8. At each portionof the plug structure the sealing elements are of basically L-shapedcross-sectional configuration and are retained in mechanicallyinterlocked relation with the plug structure by means of the variousretainer elements. By providing for retention of the sealing elements inthis manner, the sealing elements will resist any tendency to beextruded or pulled from the respective grooves under the influence ofpressure or velocity induced forces caused by the fluid flowing throughthe valve.

In the event the sealing elements should become worn or damaged to theextent that replacement is necessary, the retainer elements may beseparated from the plug structure and the sealing elements may be verysimply removed. After replacement of the sealing elements, the retainerelements may again be bolted in place as shown in FIGS. 7-10.

As the plug member moves downwardly from the lifted position of FIG. 6to the fully seated position of FIG. 4, an initial seal will bedeveloped as the sealing elements initially contact the sealing surfacesof the valve body. At this time, pressure within the valve chamber willsubstantially equal the pressure within the flow passages. As the plugmember is then moved further downwardly to its fully seated position,pressure within the smaller or lower portion of the valve chamber tendsto increase as the fluid therein is compressed. Simultaneously, pressurewithin the larger or upper portion of the valve chamber tends todecrease below line pressure due to the vacuum forming effect created bydownward movement of the plug member. Obviously, operation of the valveactuator is retarded as the plug member is moved into fully seatedrelationship within the valve body due to development of such positiveand negative pressures.

The valve actuator can move the plug, but with some difficulty. When thefluid is a liquid or other substantially incompressible medium, acondition of hydraulic lock can develop which can prevent or severelyretard movement of the plug. In accordance with this invention, and asshown in FIG. 7, the partition portion 34 of the plug member may beformed to define an equalizing passage 147 that allows free interchangeof fluid between the chambers above and below the plug member, therebymaintaining equalized pressure within these chambers. In large sizedvalves several quarts of fluid will flow through the equalizing passage147 with pressure in the upper and lower chambers remainingsubstantially balanced.

Due to the tapered nature of the plug member, the surface area of theupper portion of the plug greatly exceeds the surface area of the lowerportion thereof. After initial sealing contact has been established,continued seating movement of the plug member tends to develop positiveand negative valve chamber pressures as discussed hereinbelow. Theequalizing passage 147, however, allows the development of a balancedpressure condition within the valve chamber, but this balanced pressurewill nevertheless be lower than line pressure. The much greater surfacearea of the large extremity of the plug member can result in thedevelopment of a severe negative pressure condition that can severelyretard actuation of the valve by the valve actuator, resulting inundesirable wear of the valve actuator and requiring a much moreexpensive and higher rated valve actuator mechanism in order toaccomplish satisfactory operation. Although maintenance of a pressuredifferential between line pressure and valve chamber pressure isadvantageous for reasons identified hereinbelow, the present inventionprovides means for limiting the effect of the negative pressure that isestablished as the plug member of the valve is fully seated.

As illustrated in FIG. 4, the bonnet structure 28 is shown to be formedto define a passage 166 to which is threadedly connected a conduit 168that may have a control valve 170 connected therein. The bonnetstructure is also formed to define a passage 172 within which isconnected a conduit 174 that may have a control valve 176 connectedtherein. The passage 172 of the bonnet structure is brought intoregistry with a passage 178 formed in the valve body and a bridgecoupling 180 is utilized to provide sealed communication across thejoint between the bonnet and valve body. The bridge connection 180 isinternally bored to communicate fluid from passage 172 to the passage178 of the valve body. Conduits 168 and 174 are bridged by a pair ofparallel conduits shown schematically at 169 and 171, each havingadjustable check valves 173 and 175, respectively. The fluidcommunication that is established between the valve chamber and flowpassage by valved conduits 168 and 174 together with the valve body andbonnet passages and bridge conduits 169 and 171 may best be defined as apositive and negative pressure limiting system. The pressure limitingsystem has the effect of maintaining the pressure differential betweenthe valve chamber and flow passage at predetermined values asestablished by respective ones of the variable check valves 173 and 175.The pressure limiting system also has the effect of bleeding fluideither to the flow passage or from the flow passage responsive tovolumetric changes that occur within the valve body due to movement ofthe plug member. For example, when the plug member is shifted upwardlyduring unseating, the large area of the plug member displaces asubstantial volume of fluid during the unseating operation. Some of thedisplaced fluid will flow through the pressure balancing passage 147 tothe lower, smaller portion of the valve chamber, but, unless otherwisecompensated for, the displaced fluid could develop an increased pressurewithin the valve chamber that is sufficient to stall or at leastinterfere with the valve actuator. Moreover, seating or unseating theplug member at high pressure differential across the sealing members ofthe valve can result in severe damage to the sealing members of thevalve can result in severe damage to the sealing members due to pressureextrusion, erosion and cutting of the sealing members. When the plugmember is moved upwardly, pressure can increase only to the valvedetermined by the pressure setting of check valve 173. As the plugmember continues to be moved upwardly, the check valve 173 unseats andvents the excess fluid through conduit 174 and passages 172 and 178 intothe flow passage 20. The pressure differential across the sealingmembers will not exceed the pressure setting of the check valve, such as25 psig, for example.

As the plug member is moved downwardly toward the fully seated positionthereof, initial sealing engagement will occur at some intermediateposition. Thereafter, further downward movement of the plug member willresult in the development of a negative pressure within the valvechamber again due to the substantially greater surface area at the largeextremity of the plug member as compared with the smaller extremitythereof. If the setting of the check valve 175 is 25 psig, for example,as soon as the negative pressure within the valve chamber decreases to25 psig, further volumetric fluid displacement resulting from furtherdownward movement of the plug member will result in unseating of thecheck valve. Fluid from the flow passage 20 will enter the valve chamberthrough the pressure limiting system. The maximum pressure differentialexisting across the sealing elements of the valve at any time will be 25psig in this situation. Of course, the variable check valves allow thepositive and negative pressure differential ranges to be set at anydesired value or set at differing values. Typical variable check valvesfor accomplishing pressure limiting may take the forms illustrated inFIGS. 14 and 15, discussed in detail hereinbelow. When four-way plugvalves are utilized in meter prover systems, it is especially desirableto detect any leakage across the sealing elements. Any inaccurate flowmeasurement that occurs must be deleted in order to determine theaccuracy of the flowmeter being tested.

In the valve construction of FIG. 4, with the valve element seated atone of the sealing and diverting positions thereof, there will exist aslight pressure differential across the valve element. Since the valveconstruction is a four-way diverter valve that is designed for use inmeter prover systems and other systems where flow diversion is employed,the upstream and downstream sides of the valve chamber may be in fluidcommunication as shown in FIGS. 1 and 3. The spherical plug, however,has frictional engagement with the internal surfaces of the meter proverconduit and thus, must be moved within the conduit. The amount ofpressure required to overcome the frictional engagement of the sphere,i.e. about 5 p.s.i., for example, will exist as a pressure differentialacross the valve element. It is necessary that the sealing elements ofthe tapered plug member 34 establish positive sealing at each sealingposition thereof because any leakage, no matter how insignificant willresult in an inaccurate meter prover measurement.

As the valve element is seated, a negative pressure will be developedwithin the valve chamber as compared to line pressure. If the sealingelements of the valve are sealing properly, the pressure differentialbetween the line and valve chamber will be maintained. A pressure gauge184 will monitor the pressure within the valve chamber 14. If the valvechamber pressure should be steadily increasing as indicated by thepressure gauge, after the plug member has been seated, such pressurechange would be evidence that the integrity of the seal is not properlyestablished. The measurement taken must be disregarded in such event.Leakage may occur simply when sand, line scale or other debris mighttemporarily interfere with the sealing ability of the sealing element.As valve seating occurs, the pressure gauge should evidence pressurereduction within the valve chamber. Then the gauge pointer should remainstable until unseating movement is initiated. Control valve 170 and 176may be closed to prevent the interchange of fluid between the valvechamber and flow passage, if it is desired to service the check valvesor pressure gauge without shutting down the flow line or meter proversystem controlled by the valve. More importantly, however, the valves170 and 176 provide a means for isolating the check valves in order thatthey may be checked for leakage. By selectively operating the controlvalves 170 and 176 it can be determined whether leakage, if any, isoccurring at the seals of the valve element or at the check valves.

In circumstances where a pressure limiting fluid interchange is notutilized and with fluid, especially a liquid, entrapped in the valvechamber above and below the plug member 34, a condition commonlyreferred to as hydraulic locking may occur. This condition may preventor severely retard the ability of the valve actuator to impart upwardmovement to the plug member. In order to move upward, the plug membermust displace a certain amount of the liquid of gaseous medium disposedin the valve chamber and above the plug. Since a liquid is substantiallyincompressible, the plug member may be prevented from displacing theliquid and moving upwardly unless the fluid is forced past the sealingmembers during seating and unseating movement. It desirable therefore toprovide means for insuring an ability to displace a liquid or gaseousmedium from upper and lower closed portions of the valve chamberstructure, thus allowing the valve actuator to simply and efficientlyoperate the plug element between desired operating positions withinencountering any severe opposing forces. One suitable means providingfor displacement of liquid or gaseous medium from the closed spaceimmediately above the rotatable plug element 34 may conveniently takethe form illustrated in FIG. 11 where a pressure transmission conduit171 is shown to be connected to the bonnet structure 28 in communicationwith a pressure transmission passage 173. A differential accumulator isillustrated generally at 175 and includes an accumulator body 177 thatis formed internally to define large and small piston bores 179 and 181.A differential piston 183 is movably positioned within the housing 177and defines large and small piston portions 185 and 186, respectively,having close fitting relation with the respective internal cylindricalsurfaces 179 and 181 defining the piston bores. Annular sealing elements188 and 190, such as O-rings or the like, are received within sealgrooves formed in the respective piston portions of the differentialpiston 183 to establish sealed relationship between the respectivepiston portions and cylindrical surfaces. The differential pistoncooperates with the housing structure 177 to define large and smallspring chambers 192 and 194 containing compression springs 196 and 198,respectively, and also defines a vent chamber 200 that is communicatedwith the atmosphere by means of a vent passage 202. A closure element204 having an externally threaded portion is received within the outerthreaded extremity of the larger bore 179 and provides a retainingfunction to retain the compression spring 196 within the chamber 192. Asecond pressure transmission conduit 206 may be connected to the closureelement 204 in communication with a vent passage 208 defined in theclosure element. The vent conduit may be connected at the oppositeextremity thereof to the bonnet structure 28 in communication with apressure transmission passage 210 that communicates across a bridgeconnector 212 with a vent passage 214 formed in the valve body.

When it is desired to impart upward movement to the plug element 34within the valve chamber 14, an upward linear force is applied by thevalve actuator to the valve stem 36. As the plug member begins upwardmovement, any fluid entrapped within the space between the bonnet andupper portion of the plug member will be displaced through passage 173and conduit 171 to the differential accumulator 175. The differentialaccumulator piston 183 will then begin movement to the right under theinfluence of pressure within chamber 194, being assisted by thecompression of spring 198 and being opposed by the compression ofsprings 196. Movement of the piston element 183 to the right will alsobe opposed by any pressure within chamber 192 which acts upon the largersurface area of piston portion 185. In other words, for the pistonelement 183 to move to the right under the influence of pressuretransmitted from the valve chamber the pressure transmitted, togetherwith the force of compression spring 198, must exceed the pressure andspring induced force developed at the larger end of the differentialpiston element. When the pressure of the vented fluid is sufficientlygreat to move the piston in this manner, any fluid contained in chamber192 will be forced through conduit 206 and passages 210 and 214 into theflow passage of the valve.

The differential accumulator system will insure that the pressurecontained within the valve chamber above the piston element 34 willexceed the pressure within the flow passage of the valve, thus placingthe plug member 34 under positive pressure sealing. A pressure inducedforce will be developed on the plug member that will urge the plugmember downwardly, thus causing the sealing elements 140 and 142 to bemechanically induced into tighter sealing engagement with the seatingsurfaces of the valve body. Should pressure within the space between theplug member and the bonnet be lower than line pressure, line pressureacting through conduit 206 and introduced into chamber 192 will urge thedifferential piston element 183 against the compression of spring 198.By virtue of the smaller surface area of smaller piston portion 186, thedifferential piston will develop a higher pressure in chamber 194 whichwill be communicated through the vent conduit 171 and vent passage 173into the valve chamber. This higher pressure will act upon the plugmember, positively urging the plug member downwardly into pressureenhanced sealing engagement with the seating surfaces defined within thevalve chamber. Positive pressure sealing is thus effectuated and toenhance the sealing ability of the valve and venting of body fluid isalso allowed in order to promote ease of valve actuation.

Referring now to FIG. 12, valve body venting and positive pressuresealing is shown to be promoted by an alternative valve mechanismincluding a substantially identical basic valve construction as in FIGS.4, 6 and 11 but incorporating different external components and fluidcircuitry for accomplishment of the same. The valve element will not beprovided with passages, such as at 147 in FIG. 7, because pressurebalancing within the upper and lower portions of the valve chamber isnot desirable. As shown in FIG. 12, the trunnion element 38 is shown toextend through a packing and bearing retainer element 220 and into aninternal bore 222 defined within an accumulator housing 224 that issecured to the valve body structure by a plurality of bolts 226 whichextend through a flange 228 of housing 224 and are received withinappropriate internally threaded apertures defined within the valve body12. An annular sealing element 230 is received within an internalannular groove defined within the housing 224 and establishes sealingengagement between the housing and the trunnion element 38. Within thehousing structure 224 is movably positioned a piston element 232 whichis maintained in sealing engagement with respect to the housingstructure by means of an annular sealing element 234 that is retainedwithin an appropriate seal groove defined internally of the housingstructure. The piston element 232 is urged toward the trunnion 38 bymeans of an adjustable compression spring 236 that is located within aspring chamber 238 defined within the housing. A spring adjustment cap240 is internally threaded and is received by external threads 242defined by the housing 224. A spring retainer element 246 that isreceived by an internally threaded portion of the bore 222 may beadjusted relative to the housing structure in order to achieveadjustment of the force induced to the piston element 232 by thecompression spring 236.

The accumulator housing 224 may be formed to define a first fluidinterchange passage 248 to which may be interconnected a fluidinterchange conduit 250 incorporating an adjustable control check valve252 that may be set by an adjustment mechanism 254 to allow flow offluid from the accumulator chamber 256 when fluid pressure within theaccumulator chamber exceeds the pressure setting of the control check252. The opposite extremity of the fluid interchange conduit 250 may beconnected to the bonnet structure 28 for communication of fluid into thespace between the plug and bonnet structure. Another conduit 258 may beconnected to the bonnet structure and may be communicated at oneextremity with the space between the bonnet and plug and at the oppositeextremity may communicate with a passage 260 that opens into a fluidpassage of the valve. A check valve 262 may be incorporated into conduit258 for the purpose of allowing unidirectional flow of fluid from theflow passage of the valve into the space between the bonnet and plug. ;pA fluid pressure control conduit 264 may also be connected to the bonnetstructure 28 for communication with the space between the bonnet andplug. A control check valve 266 may be connected into the conduit 264and may be controlled by means of a pressure adjustment mechanism 268when it is desired to lift the plug member 34 preliminary to arotational operation control check valve 252 and check valve 262 willnot allow displacement of fluid from the space between the bonnet andplug. Consequently, control check valve 266, the control pressure ofwhich may be set at line pressure "P" plus the positive pressure inducedby the accumulator, which is referred to as "Delta P," will allowdisplacement of fluid through the conduit 264.

To facilitate displacement of fluid from the chamber between the valvebody and the lower portion of the plug member, a vent conduit 270 willbe connected to the valve body, as schematically shown in FIG. 12. Theopposite extremity of the conduit 270 will be connected to theaccumulator housing 224 is communication with a passage 272communicating with the accumulator chamber 256. A check valve 274 may beconnected into the conduit 270 and will be operative to allow fluidwithin the chamber 14 below the plug element to be displaced into theaccumulator chamber. The fluid so displaced will act upon the pistonelement 232 forcing the piston element downwardly against thecompression of the spring 236.

The compression of spring 236 will be adjusted so as to develop a forceacting upon piston 232 that develops a fluid pressure within theaccumulator chamber that is substantially equal to line pressure "P"plus accumulator pressure, "Delta P." The control check valve 252 willalso be adjusted to allow the flow of fluid in fluid interchange conduit250 when the pressure in the accumulator chamber substantially equalsline pressure plus accumulator pressure. As the plug element 34 is moveddownwardly by the valve actuator, after initial seal contact has beenestablished further downward movement will displace fluid from the spacebetween the plug and the body structure through conduit 270 and checkvalve 274 into the accumulator chamber. After the plug seal has beenestablished, continued downward movement of the plug element willdevelop a reduced pressure condition within the scope between the bonnetand the upper portion of the valve body. Fluid from the accumulatorchamber will therefore flow through the control check valve 252 andconduit 250 and will enter the space between the bonnet and the upperportion of the plug element.

As the plug member is moved downwardly by the valve actuator, thetrunnion element 38 will move downwardly within the piston bore 222thereby forcing the piston member 232 downwardly against the compressionof spring 236. As mentioned above, th spring 236 is set at P+Delta P.The control check valve 252 will therefore bleed fluid into the valvechamber. When the plug member is seated, fluid in the accumulatorchamber will bleed through fluid interchange conduit 250 into the spacebetween the bonnet structure and the upper portion of the plug member.Thus, within the valve chamber 14 there will be maintained a pressurecondition of P+Delta P and this positive pressure condition will developa force acting upon the plug member that urges the plug member intomechanically greater sealing engagement with the valve body structure.

Referring now again to FIG. 4 and also to FIG. 13, it is desirable toprovide means for properly positioning the plug element with respect tothe valve body structure to insure optimum sealing engagement,especially between the straight sealing portions of the plug member andthe seating surfaces 16 of the valve body. In accordance with thepresent invention, an adjustment member 280 may be provided that isreceived within an opening 282 defined in the bonnet structure 28. Aneccentric portion 284 of the adjustment element 280 extends into thevalve chamber 14 and is positioned for engagement by a stop element 286defined at the upper portion of the plug element 34. During valveoperation, the plug element is rotated by the valve actuator 52 untilthe stop element 286 engages the cam portion 284 of the adjustmentelement 280. At this time proper positioning of the plug element hasoccurred and the valve actuator will shift the plug member 34 downwardlyinto sealing engagement with the valve body.

As shown in FIG. 13, the positioning element 280 will be provided with aflange portion 288 having a plurality of apertures 290 formed therein.As shown, the apertures are positioned on 15° centers and may be broughtinto registry with internally threaded apertures formed in the bonnetstructure. If it is desired to adjust the stopping position of the plugelement 34, adjustment element 280 may be unbolted from the bonnet andmay be rotated one or more apertures relative to the bonnet and mayagain be secured in place by the bolts. As shown diagrammatically bymeans of broken lines in FIG. 13, an 180° adjustment of element 280 willadjust the position of contact between the cam 284 and the stop element286 by the amount shown by opposed arrows. If any wear occurs thatrequires slight shifting of the adjustment element, it is not necessaryto disassemble the valve in order to achieve proper stopping position ofthe plug. By simply unbolting the adjustment element, rotating it adesired number of aperture increments and rebolting it in place, plugpositioning adjustment can be accomplished. This adjustment operationcan be accomplished in a few minutes time using simple wrenches andtools. Moreover, it is not necessary to shut down the valve controlledflow system for extended periods of time merely to achieve adjustment ofplug stopping position. Also, it is not necessary to provide forposition adjustment by means of adjusting the internal operationalmechanism of the valve actuator. The valve actuator can therefore be ofrelatively simple and inexpensive design without detracting in any wayfrom the commercial feasibility of the present invention.

As mentioned above, it is desirable to provide means for achieving fluidinterchange between the valve chamber 14 and flow passage 20 to allowcompensation for volumetric changes as the plug member is seated andunseated. As shown in FIG. 4, a pair of conduits 168 and 174 areinterconnected by variable check valves 173 and 175 and allow fluidinterchange to occur while maintaining pressure diferential between thevalve chamber and flow passage within predetermined limits. Simplicationof the fluid conduit and valve system illustrated schematically in FIG.4 may conveniently take the form of double relief valve mechanismsillustrated particularly in FIGS. 14 and 15.

As shown in FIG. 14, a fluid interchange conduit may be provided havingconduit section 168 and 174 having the opposite extremities of theseconduit sections in communication with the valve chamber and flowpassage, respectively, as shown in FIG. 4. As the valve element 34 isseated and unseated, a high volume flow is induced in lines 168 and 174.A check to control such flow must operate at low pressure differential,must allow high volume flow and must develop a positive seal. A doublerelief valve mechanism is shown in FIGS. 14 and 15 which effectivelyprovides these features. Each valve portion of this valve constructionallows unidirectional flow of fluid within individually preset pressureranges. The double relief valve mechanism incorporates a valve bodystructure 300 that is formed to define inlet and outlet passageways 302and 304 that are intersected by valve chambers 306 and 308,respectively. Within the valve chambers are received relief valvemechanism illustrated generally at 310 and 312. The relief valves are ofessentially identical configuration and, for purposes of simplicity,only one of the relief valves 312 will be discussed in detail.

Relief valve 312 includes a housing structure 314 defining an annularexternal flange 316 that is received by a retainer element 318 by whichthe housing structure may be secured to the body structure 300 by meansof bolts 320. An internal portion 322 of the housing 312 is receivedwithin the bore 308 and is sealed with respect to the bore by means ofan annular sealing element 324 which may conveniently take the form ofan O-ring, or any other suitable sealing element, received within anannular seal groove formed in the housing 314.

The housing 314 is formed internally to define a bore 326 within whichis received a sleeve type plunger 328 defining a spring receptacle 330.At one extremity of the sleeve element 328 may be provided a sealsupport element 332 defining a cylindrical surface 334 that isreceivable in press fitted immovable position at the outer extremity ofthe sleeve. The support element is also formed to receive a bolt orscrew element 336 by which a seal retainer element 338 may be secured tothe support element in such a manner as to retain an annular sealingelement 340 in positively retained relation with the plunger. Within thevalve body structure 300 at the inner extremity of the bore 308 isformed a frusto-conical seat surface 342 that is engageable by the sealelement 340 when the plunger element is seated in the manner shown bythe relief valve mechanism 310. The support element 332 is also formedto define a projecting guide portion 344 which cooperates with a guideportion 346 defined on a springs adjustment element 348 to support acompression spring 350 within the springs receptacle 330. An adjustmentelement 348 is movably received within a reduced diameter bore 352formed in the housing 314 and is maintained in sealed relationship withrespect to the housing 314 by an annular sealing element 354, such as anO-ring or the like, that is received within a seal groove formed in thesprings adjustment element. The outer portion of the housing structureis formed to define an internally threaded opening 356 that receives anexternally threaded adjustment element 358. A lock nut 360 is receivedby the external threads of adjustment element 358 and serves to lock theadjustment element at desired positions thereof. The compression of thespring 350 determines the opening pressure of each of the valvemechanisms 310 and 312 and, thus each of the of valves may beindividually adjusted by means of the adjustment elements 358 so as toprovide for selective opening pressures. It is not necessary that theopening pressures of the valves be identical. The opening pressures maybe individually set depending upon the characteristics of flow desiredin either direction through the fluid interchange conduit. Within thevalve body structure 300 is defined a pair of ports 362 and 364 thatcommunicate respective ones of the valve chambers to conduits 168 and174.

Operation of the relief valve mechanism of FIG. 14 is as follows:Assuming that flow of fluid occurs in the direction of the flow arrowsand the opening pressure of valve 312 is exceeded, the plunger sleeve328 will shift to the left after the sealing element 340 has separatedfrom the seat surface 342. Depending upon the pressure encountered, thesleeve element may move completely to the left and may engage the stopshoulder 329. After this has occurred, flow of fluid from conduitsection 174 will flow through port 362 across the valve seat 342 andbore 308, whereupon the flowing fluid will enter conduit section 168through bore 302. As shown with respect to relief valve structure 310,the sleeve elements 328 are each formed to define a plurality ofapertures 366. With the direction of fluid flow as shown in FIG. 14, thepressurized fluid medium will enter the valve receptacle bore 306 andwill pass through apertures 366 into the interior of the sleeve element328. Pressure within the sleeve element will act upon the surface areaof the sleeve element defined by its seal with the seat surface therebydeveloping a force that urges the sleeve element of relief valve 310into pressure enhanced sealing engagement with the seat surface.

In other words, fluid pressure opens one of the relief valves andsimultaneously enhances the sealing ability of opposite relief valve.When the direction of fluid flow through the valve mechanism isreversed, the opposite situation will occur. Relief valve 310 will besusceptible of being opened if the fluid pressure exceeds the springenhanced opening pressure thereof. At the same time, this direction offlow also creates a pressure induced force acting upon sleeve or plungerelement 328 that forces the sealing element 340 thereof into pressureinduced sealing engagment with seat surface 342. By employing a reliefvalve mechanism as illustrated in FIG. 14, it is not necessary toincorporate parallel conduit lines such as shown in FIG. 4. In the eventdifferent valve opening pressures are desired, depending upon thedirection of fluid flow through the relief valve mechanism, this can beaccomplished simply by adjusting the spring compression of each of thevalve mechanisms as desired.

Double valve relief valve mechanisms may take other suitable forms andanother of these forms is illustrated in FIG. 15 where a relief valvemechanism is shown generally at 370 having a relief valve body structure372 to which dampening liquid displacement conduits 168 and 174 areconnected by threading or by any other suitable means of connection.Internally, the valve body structure 372 is formed to define inlet andoutlet passageways 374 and 376 that are in communication with a pair ofvalve chambers 378 and 380. Ports 382 and 384 are also defined withinthe valve body structure for the purpose of communicating the valvechambers with the inlet and outlet passageways 374 and 376,respectively.

Within each of the valve chambers is located a relief valve mechanism,illustrated generally at 386 and 388. For purposes of simplicity, onlythe structure of relief valve 388 will be discussed in detail since therelief valves 386 and 388 are of substantially identical construction.Relief valve 388 incorporates an elongated sleeve element 390 havingperforations 392 formed therein. Sleeve element 390 also is formed todefine a pair of annular seal grooves within which are located annularsealing elements 394 and 396. Sealing element 396 establishes sealingengagement with a cylindrical internal surface 398 defining a portion ofthe wall structure of the valve chamber 380. The opposite sealingelement 394 establishes sealing engagement with an internal cylindricalsurface 400 defined within a closure element 402 that is secured to thebody structure 372 by means of bolts 404. An external sealing element406 supported within an external groove formed in the closure element402 establishes sealing engagement with the internal cylindrical surface408 that cooperates with the closure structure to define the valvechamber 380.

A resilient check valve sleeve 410 is supported about the periphery ofthe perforated sleeve element 390 by a retainer band 412. The sleevevalve 410 is formed of a resilient material, such as rubber, viton orany other suitable elastomeric material, and is capable of yieldingresponsive to pressure to allow flow of fluid to occur through theperforations 392. As pressurized fluid flows through conduit 174, asshown by the flow arrow, fluid will flow through port 384 and will enterthe sleeve element 390. The fluid will then unseat the flexible sleeveelement 410 in the manner shown by check valve element 388 thereforeallowing flow through the perforations 392 and into passage 374.Simultaneously, fluid from flow passage 174 will enter valve chamber 378and will act upon the outer periphery of the resilient sealing elementof check valve 386. When this occurs, the flexible sleeve type checkvalve will prevent fluid flow through valve 386.

Upon reversal of flow in conduits 168 and 174, fluid will act upon theouter periphery of the resilient sleeve 410 of check valve 388, causingit to seat positively thereby preventing any flow across the check valve388. Simultaneously, this fluid will enter valve chamber 378 throughport 382 and will act through the perforations on the inner periphery ofthe resilient sleeve valve of check valve 386. This will cause the valvesleeve to yield in the manner shown by valve 388, thereby allowing flowacross check valve 386 into the valve chamber 378 and thence into theflow passage 376. By employing the plural check valve mechanism 370, asingle conduit fluid displacement system may be incorporated forpurposes of dampening rather than the parallel conduit circuitryillustrated in FIG. 2.

In view of the foregoing, it is apparent that the present invention isadapted to attain all of the objects and features hereinabove set forth,together with other features that are inherent from the apparatusitself. It will be understood that certain combinations andsubcombinations are of utility and may be employed without reference toother features and subcombinations. This is contemplated by and iswithin the scope of the present invention.

As many possible embodiments may be made of this invention withoutdeparting from the spirit and scope thereof, if is to be understood thatall matters hereinabove set forth or shown in the accompanying drawingsare to be interpreted as illustrative and not in any limiting sense.

What is claimed is:
 1. A rotary lift-turn type diverter valve mechanismfor controlling the flow of fluid, said valve mechanism comprising:avalve body defining a frusto-conical valve chamber and defining aplurality of flow passages disposed in intersecting relation with saidvalve chamber; a bonnet structure being connected to said valve body anddefining a closure for said valve chamber; a generally frusto-conicaldiverter element being movably positioned within said valve chamber andincluding a valve stem extending in sealed relation through said bonnetand a trunnion being journaled by said valve body and positioned incoaxial relation with said valve stem, said diverter element cooperatingwith said valve body to define flow passage means; adjustable diverterpositioning means being provided by said valve mechanism; diverterpositioning means being provided on said diverter element andcooperating with said adjustable diverter positioning means forprecisely orienting said plug element with respect to said inlet andoutlet passages said adjustable diverter positioning means beingselectively positionable to correct for minor misalignment of saiddiverter element with respect to said flow passage means; and valveactuator means being connected to said valve body and operativelyengaging said valve stem, said valve actuator means being capable ofimparting both linear and rotary components of movement to said valvestem during operation for unseating, rotating and reseating saiddiverter element within said valve chamber.
 2. A rotary lift-turndiverter valve mechanism as recited in claim 1, wherein said adjustablediverter positioning means comprises:positioning means being formed inone of said valve body and bonnet structure; and a diverter positioningelement being retained by said positioning means and defining a stopengagement surface, said diverter positioning means engaging said stopengagement surface to achieve positioning of said plug element relativeto said inlet and outlet passages, said positioning means beingadjustable to change the position of engagement between said diverterpositioning means and said eccentric stop engagement surface.
 3. Arotary lift-turn diverter valve mechanism as recited in claim 2,wherein:said diverter positioning element is externally adjustable toselectively position said plug element relative to said inlet and outletpassages.
 4. A rotary lift-turn type diverter valve mechanism as recitedin claim 2, wherein said positioning means comprises:a positioningaperture being formed in one of said valve body and bonnet; said one ofsaid valve body and bonnet is formed to define a plurality of internallythreaded bolt apertures about said positioning aperture; and saiddiverter positioning element is formed to define a plurality of boltopenings through which bolts extend for securing said diverterpositioning element to said one of said valve body and bonnet, saidadjustment of said diverter positioning element being achieved byselective alignment of said bolt openings relative to said boltapertures.
 5. A rotary lift-turn type diverter valve mechanism asrecited in claim 2, wherein:said diverter positioning element is formedto define an eccentric stop engagement surface, the position of saidstop engagement surface being selectively altered by said positioningmeans for selective positioning of said diverter element relative tosaid inlet and outlet passages.
 6. A rotary lift-turn type plug valvemechanism as recited in claim 1, wherein:said bonnet structure is formedto define a positioning aperture and first adjustment means; and saiddiverter positioning means is formed to define second adjustment meansfor cooperative engagement with said first adjustment means to achieveselective positioning of said stop engagement surface for positioning ofsaid diverter element relative to said inlet and outlet passages.
 7. Arotary lift-turn type diverter valve mechanism as recited in claim 1,wherein said adjustable diverter positioning means comprises:apositioning aperture being formed in said bonnet structure and saidbonnet structure being formed to define a plurality of adjustmentapertures about said positioning aperture; and said positioning meansbeing formed to define a plurality of adjustment openings through whichbolts extend for securing said positioning means to said bonnetstructure, said adjustment of said positioning means being achieved byselective alignment of said bolt openings relative to said boltapertures.
 8. A rotary lift-turn type diverter valve mechanism asrecited in claim 1, wherein said mechanism includes:plug dampening meansfor applying a dampening force to said plug element to prevent slammingof said diverter element upon reaching said diverter positioning meansand to dampen mechanical shock due to fluid induced force changes actingduring movement of said diverter element.
 9. A rotary lift-turn typeplug valve mechanism as recited in claim 8, wherein said dampening meanscomprises:means defining a plurality of dampening chambers; volumevarying means being movable responsive to movement of said plug elementand being operative to increase the effective volume of one of saiddampening chambers and simultaneously reduce the effective volume of theother one of said dampening chambers; dampening fluid being disposed inat least one of said dampening chambers; dampening passage meansinterconnecting said dampening chambers; and dampening control meansrestricting the flow of said dampening fluid between said dampeningchambers.
 10. A rotary lift-turn type diverter valve mechanism asrecited in claim 9, wherein said volume varying means comprises:adampening housing; and a vane element being movably positioned withinsaid dampening housing and dividing said dampening housing into twovariable volume dampening chambers, said vane element being rotatableresponsive to movement of said diverter element.
 11. A rotary lift-turntype diverter valve mechanism as recited in claim 10, wherein:saiddampening housing is provided externally of said valve body; and saidvane element is nonrotatably connected to said trunnion and movabledirectly by said trunnion.
 12. A rotary lift-turn type diverter valvemechanism as recited in claim 9, wherein:said dampening passage meansincludes first and second passage means connected in schematicallyparallel relation; first relief valve means being provided in said firstpassage means for controlling the flow of dampening fluid from one ofsaid dampening chambers to the other of said dampening chambers; andsecond relief valve means being provided in said second passage meansfor controlling the flow of dampening fluid from said other of saiddampening chambers to said one of said dampening chambers.
 13. A rotarylift-turn type diverter valve mechanism as recited in claim 9, wherein arelief valve assembly is interconnected into said dampening passagemeans, said relief valve assembly comprising:a relief valve housingdefining inlet and outlet passage means and defining a pair of valvechambers; relief valve mechanisms being disposed within each of saidvalve chambers, said relief valve mechanisms being oriented such thatapplication of fluid pressure to one of said inlet and outlet passagemeans will urge one of said relief valve mechanisms toward the openposition thereof and will urge the other one of said relief valvemechanisms toward the closed position thereof and application of fluidpressure to the other one of said inlet and outlet passages will urgesaid one of said relief valves toward the closed position thereof andwill urge said other of said relief valves toward the open positionthereof.
 14. A rotary lift-turn type diverter valve mechanism as recitedin claim 12, wherein:said relief valve mechanisms are individuallyadjustable to selectively vary the opening pressure thereof and therebyselectively vary the dampening of said plug element in either directionof movement thereof.
 15. A rotary lift-turn type diverter valvemechanism as recited in claim 13, wherein:said relief valve mechanismsare spring urged and are individually adjustable to selectively vary theopening pressure thereof and thereby selectively vary the dampening ofsaid plug element in either direction of movement thereof.
 16. A rotarylift-turn type diverter valve mechanism for controlling the flow offluid, said valve mechanism comprising:a valve body defining afrusto-conical valve chamber and defining inlet and outlet passagesdisposed in intersecting relation with said valve chamber; a bonnetstructure connected to said valve body and defining a closure therefor;a frusto-conical diverter element being positioned for both linear androtary movement within said valve chamber and including a valve stemextending in sealed relation through said bonnet and a trunnionextending in coaxial relation with said valve stem and being journaledfor rotation and linear movement relative to said valve body, said plugelement cooperating with said valve chamber in the seated position ofsaid plug element to define a first valve chamber space between oneextremity of said plug element and said valve body and a second valvechamber space between the opposite extremity of said plug element andsaid valve body; and at least one pressure equalizing passage beingformed in said diverter member and terminating at each axial extremityof said diverter member, at least some of the fluid within said valvechamber is displaced through said equalizing passage means duringseating and unseating movement of said diverter element, said equalizingpassage facilitating equalization of fluid pressure within said firstand second valve chamber spaces.
 17. A rotary lift-turn type divertervalve mechanism for controlling the flow of fluid, said valve mechanismcomprising:a valve body defining a frusto-conical valve chamber anddefining inlet and outlet passages disposed in intersecting relationwith said valve chamber; a bonnet structure connected to said valve bodyand defining a closure therefor; a frusto-conical diverter element beingpositioned for both linear and rotary movement within said valve chamberand including a valve stem extending in sealed relation through saidbonnet and a trunnion extending in coaxial relation with said valve stemand being journaled for rotation and linear movement relative to saidvalve body; and fluid interchange means interconnecting said valvechamber and at least one of said inlet and outlet passages, said fluidinterchange means comprising: passage means interconnecting said valvechamber and said one of said inlet and outlet passages; and relief valvemeans controlling communication through said passage means and beingoperative to allow flow in either direction through said passage meansresponsive to sensing pressure in excess of a predetermined minimum,said fluid interchange means compensating for volumetric changes withinsaid valve chamber as said plug element is moved linearly during seatingand unseating movement and maintaining the pressure differential betweensaid valve chamber and said one of said inlet and outlet passages withina predetermined pressure range.
 18. A rotary lift-turn type divertervalve mechanism as recited in claim 17, wherein said relief valve meanscomprises:a pair of oppositely directed relief valves being communicatedwith one another and communicated with said passage means, one of saidrelief valves allowing flow in one direction and preventing flow in theopposite direction, said one of said relief valves being adjustable forcontrolling the relieving pressure thereof, the other one of said reliefvalves blocking the flow of fluid in said one direction and allowing thefluid in said opposite direction, said other one of said relief valvesalso being adjustable for controlling the relieving pressure thereof,said relief valves being cooperatively related for controlling pressurerelieving and fluid flow in both directions through said passage means.19. A rotary lift-turn type diverter valve mechanism as recited in claim18, wherein:opening pressure for one of said relief valves enhances thesealing of the opposite one of said relief valves.